1. Field of the Invention
The present invention relates to a control and supervisory signal transmission system, and in particular, to a control and supervisory signal transmission system wherein a parallel control signal from a controller is converted into a serial signal to transmit it to a remote device, serial-parallel conversion is performed in a controlled section of the remote device to drive the device, a parallel supervisory signal in a sensor section to detect the status of the device is converted into a serial signal to transmit it to the controller, serial-parallel conversion is performed on the serial signal to provide it to the controller, the control signal is superimposed on a clock signal, and the supervisory signal is superimposed on these signals.
2. Description of the Related Art
In the technical field of automatic control, it is widely practiced that a control signal is sent from a controller such as a sequence controller, programmable controller, or computer to a number of remote controlled devices (a motor, solenoid, electromagnetic valve, relay, thyristor, and lamp, for example) to drive and control them and a supervisory signal is transmitted from a sensor section to the controller to detect the status of devices (the on/off state of a switch such as a reed switch, micro-switch, and push button switch)
In such a technology, a number of lines such as a power supply line, control signal line, and ground wire are used for the interconnection between the controller and the controlled devices, and between the controller and the sensor section. Therefore a problem has arisen that wiring work becomes difficult, wiring space decreases, and wiring costs increases as packaging density increases because of the recent downsizing of the controlled devices.
There are two approach to solving the problem: a xe2x80x9csignal serial-parallel conversion systemxe2x80x9d (Japanese Patent Application No. 62-229978) and a xe2x80x9cserial transmission system of a parallel sensor section signalxe2x80x9d (Japanese Patent Application No. 62-247245). According to these systems, wiring in a transmission system between a controller and a controlled device or between the controller and a sensor section can be accomplished with a smaller number of lines because one (one bit) control signal (or sensor signal) corresponding to each clock can be superimposed on a clock signal line including power supply.
According an invention, a xe2x80x9ccontrol and supervisory signal transmission methodxe2x80x9d (Japanese Patent Application No. 1-140826), fast bidirectional signal transmission between a controller and a controlled unit and between the controller and a sensor section can be achieved by a simple configuration by connecting an input unit and an output unit to a parent station and providing a clock signal superimposed on power supply onto a common data signal line from the parent station. That is, the number of lines and the cost of wiring can be reduced, the connection arrangement of units can be simplified, and addresses can be allocated to the units at will, allowing the addition and deletion of a unit to be performed freely at a desired location.
According to the prior-art configuration describe above, fast bidirectional signal transmission between the controller and the controlled unit and between the controller and the sensor section can be achieved. However, a signal (hereinafter called a xe2x80x9ccontrol signalxe2x80x9d) from the controller to the controlled unit and a signal (hereinafter called a xe2x80x9csupervisory signalxe2x80x9d) from the sensor section to the controller cannot be transmitted at the same time because they are provided onto the common data signal line. That is, the control signal and supervisory signal can be transmitted only mutually exclusively and cannot be transmitted in two directions at the same time. Therefore a time period during which the control signal is transmitted over the common data signal line and a time period during which the supervisory signal is transmitted must be separately provided.
It is an object of the present invention to provide a control and supervisory signal transmission system, wherein a control signal and supervisory signal are superimposed on a clock signal, the control signal is a binary signal having a predetermined duty ratio, and the supervisory signal as an electric current signal is detected.
It is another object of the present invention to provide a control and supervisory signal transmission system that superimposes a multiplexed control and supervisory signal on a clock signal.
It is still another object of the present invention to provide a control and supervisory signal transmission system that superimposes a first control signal which is a binary signal having a predetermined duty ratio and a second control signal which is a voltage signal on a clock signal and superimposes a supervisory signal which is a electric current signal on those signals.
It is still another object of the present invention to provide a control and supervisory signal transmission system that superimposes a first control signal which is a binary signal having a predetermined duty ratio and a second control signal which is a voltage signal on a clock signal and superimposes a first supervisory signal which is a current signal and a second supervisory signal which is a frequency signal on those signals.
A common configuration of a control and supervisory signal transmission system of the present invention comprises a controller; a plurality of controlled devices each of which includes a controlled section and a sensor section to monitor the controlled section; a parent station connected to the controller and a data signal line common to the plurality of controlled devices; and a plurality of child stations associated with the plurality of controlled devices and connected to the data signal line and the associated controlled devices, in which a control signal from the controller is transmitted to the controlled section and a supervisory signal from the sensor section is transmitted to the controller over the data signal line.
In addition to the components of the common configuration described above, the parent station of a control and supervisory signal transmission system of the present invention comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section converts under the control of the timing signal the control signal into a serial pulse voltage signal by changing the duty ratio between a period of a voltage level other than a predetermined power-supply voltage level and the subsequent period of the power-supply voltage level in every period of the clock according to the data value of the control data signal input from the controller, and provides the converted signal onto the data signal line. The parent station input section detects under the control of the timing signal a supervisory data signal superimposed on a serial pulse voltage signal transmitted over the data signal line, in every period of the clock, as the presence or absence of a current signal generated by contention between the supervisory data signal and the power-supply voltage on the rising edge of the power-supply voltage level to extract each data value of the serial supervisory data signal, converts it into a supervisory signal and inputs it into the controller. Each of the plurality of child stations comprises a child station output section and a child station input section. The child station output section determines the duty ratio between a period of voltage level different from the power-supply voltage level of a serial pulse voltage signal and the subsequent period of the power-supply voltage level to extract the data values of a control data signal and provides data in the data values that corresponds to the child station to the corresponding controlled section. The child station input section constructs under the control of the timing signal the supervisory data signal constituted of a binary current level varying according to a value provided by the corresponding sensor section and superimposes it as the data value of the supervisory signal on a predetermined position of the serial pulse voltage signal.
According to the control and supervisory signal transmission system of the present invention, the control signal from the controller to the controlled section is made a binary signal (with the power-supply voltage level and another level) having a predetermined duty ratio and the supervisory signal from the sensor section to the controller is detected as the presence or absence of a current signal generated by contention between the binary signal and the power-supply voltage on the rising edge of the power-supply voltage level. This allows the control signal and supervisory signal to be superimposed on the clock signal. Therefore fast bidirectional signal transmission between the controller and the controlled section and between the controller and the sensor section can be achieved and the control signal and supervisory signal can be provided onto the common data signal line and transmitted bidirectionally at the same time. As a result, the need to provide separate periods for transmitting the control signal and the supervisory signal on the common data signal line can be eliminated, thus doubling the transfer rate of the signals.
In addition to the common components described above, the parent station of a control and supervisory signal transmission system of the present invention comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section converts, under the control of the timing signal, first and second control data signals into serial pulse voltage signals by changing the duty ratio between a period of a voltage level other than a predetermined power-supply voltage level and the subsequent period of the power-supply voltage level in every period of the clock according to the data value of the first control data signal input from the controller and to change the level during the period of the level other than the power-supply voltage level at a predetermined level different form the power-supply voltage or a pseudo ground level according to the data value of a second control data signal input form the controller, and provides the converted signal onto the data signal line to provide the converted signals onto the data signal line. The parent station input section detects under the control of the timing signal a supervisory data signal superimposed on a serial pulse voltage signal transmitted over the data signal line, in every period of the clock, as the presence or absence of a current signal generated by contention between the supervisory data signal and the power-supply voltage on the rising edge of the power-supply voltage level to extract each data value of the serial supervisory data signal, converts it into a supervisory signal and inputs it into the controller. Each of the plurality of child stations comprises a child station output section and a child station input section. The child station output section, under the control of the timing signal, determines the duty ratio between a period of voltage level different from the power-supply voltage level of a serial pulse voltage signal and the subsequent period of the power-supply voltage level to extract the data values of a fist control data signal or determines whether or not the level during the period of the level other than the power-supply voltage is either a predetermined voltage level different form the power-supply voltage or the pseudo ground level to extract the data values of a second control data signal, and provides data in that data values that corresponds to the child station to the corresponding controlled section. The child station input section constructs under the control of the timing signal the supervisory data signal constituted of a binary current level according to a value provided by the corresponding sensor section and superimposes it as the data value of the supervisory signal on a predetermined position of the serial pulse voltage signal.
According to the control and supervisory signal transmission system of the present invention, the first control signal from the controller to the controlled section is made a binary signal (with the power-supply voltage level and another level) having a predetermined duty ratio, the level the second control signal other than the level of the power-supply voltage level of the first control signal is made the predetermined voltage level different from the power-supply voltage or the pseudo ground level, and the supervisory signal from the sensor section to the controller is detected as the presence or absence of a current signal generated by contention between the binary signal and the power-supply voltage on the rising edge of the power-supply level. This allows the first and second control signals and the supervisory signal to be superimposed on a clock signal. Therefore, fast and bidirectional signal transmission between the controller and controlled section and between the controller can be provided, as well as the sensor section and the multiplexed (duplexed) control signal and the (non-multiplexed) supervisory signal can be provided onto a common data signal line and the signals can be transmitted bidirectionally at a time. As a result, the need to provide separate period during which the control signal or the supervisory signal is transmitted on the common data signal line can be eliminated, achieving a signal transfer rate three times faster than a conventional signal transfer rate.
In addition to the components of the common configuration described above, a control and supervisory signal transmission system of the present invention further comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section converts, under the control of the timing signal, first and second control signals into serial pulse voltage signals by changing the duty ratio between a period of a voltage level other than a predetermined power-supply voltage level and the subsequent period of the power-supply voltage level in every period of the clock according to the data value of the first control data signal input from the controller and to drive the level during the period of the level other than the power-supply voltage level to a predetermined level different form the power-supply voltage or a pseudo ground level according to the data value of a second control data signal input form the controller, and provides the converted signal onto the data signal line to provide the converted signals onto the data signal line. The parent station input section detects under the control of the timing signal a first supervisory data signal superimposed on a serial pulse voltage signal transmitted over the data signal line, in every period of the clock, as the presence or absence of a current signal generated by contention between the supervisory data signal and the power-supply voltage on the rising edge of the power-supply voltage level, detects a second supervisory data signal, which is a frequency signal superimposed on a serial pulse voltage signal transmitted over the data signal line, to extract data values of the first and second serial supervisory data signals, converts them into supervisory signals and inputs them into the controller. Each of the plurality of child stations comprises a child station output section and a child station input section. The child station output section, under the control of the timing signal, determines the duty ratio between a period of voltage level different from the power-supply voltage level of a serial pulse voltage signal and the subsequent period of the power-supply voltage level to extract the data values of a fist control data signal or determines whether or not the level during the period of the level other than the power-supply voltage is either a predetermined voltage level different form the power-supply voltage or the pseudo ground level to extract the data values of a second control data signal, and provides data in that data values that corresponds to the child station to the corresponding controlled section. The child station input section constructs under the control of the timing signal the first supervisory data signal constituted of a binary current level or the second supervisory data signal constituted of the frequency signal, according to a value provided by the corresponding sensor section superimposes it as the data value of the first or second supervisory signal on a predetermined position of the serial pulse voltage signal.
According to the control and supervisory signal transmission system of the present invention, the first control signal from the controller to the controlled section is made a binary signal (with the power-supply voltage level and another level) having a predetermined duty ratio, the level the second control signal other then the level of the power-supply voltage level of the first control signal is made the predetermined voltage level different from the power-supply voltage or the pseudo ground level, the first supervisory signal from the sensor section to the controller is detected as the presence or absence of a current signal generated by contention between the binary signal and the power-supply voltage on the rising edge of the power-supply level, and the second supervisory signal is provided as a signal having a frequency (and amplitude) different from other signals. This allows the first and second control signals and the first and second supervisory signals to be superimposed on a clock signal. Therefore, fast and bidirectional signal transmission between the controller and controlled section and between the controller and the sensor section can be provided, as well as the multiplexed (duplexed) control signal and the multiplexed (duplexed) supervisory signal can be provided onto a common data signal line and the signals can be transmitted bidirectionally at a time. That is, the control signal and the supervisory signal can be fully duplexed. As a result, the need to provide separate period during which the control signal or the supervisory signal is transmitted on the common data signal line can be eliminated, achieving a signal transfer rate four times faster than a conventional signal transfer rate.
In addition to the components of the common configuration described above, the parent station of a control and supervisory signal transmission system of the present invention further comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section converts a control data signal into a serial pulse voltage signal by driving the first or latter half of the control data signal to a predetermine power-supply voltage level and to drive the latter or first half of the control data signal to a predetermined voltage level different from the power-supply voltage level or a pseudo ground level depending on each data value of the control data signal level input from the controller in every period of the clock under the control of the timing signal, and outputs the serial pulse voltage signal onto the data signal line. The parent station input section detects a frequency signal superimposed on the serial pulse voltage signal transmitted over the data signal line in every period of the clock under the control of the timing signal to extract each data value of the serial supervisory signal and converts the data value into the supervisory signal to input the supervisory signal into the controller. Each of the plurality of child stations comprises a child station output se and a child station input section. The child station output section determines whether or not the first or latter half of the serial pulse voltage signal is the predetermined voltage level different from the power-supply voltage level or the pseudo ground level in every period of the clock under the control of the timing signal to extract each data value of the control data signal and provides data corresponding to the child station in the data value to the controlled section. The child station input section forms a frequency signal according to a value in the corresponding sensor section under the timing of the timing signal and superimposes the frequency signal on a predetermined position of the serial pulse voltage signal as the data value of the supervisory signal.
According to the control and supervisory signal transmission system of the present invention, the control signal from the controller to the controlled section is made a signal with the power-supply voltage level and another level (the predetermined voltage level or the pseudo ground level) and the supervisory signal from the sensor section to the controller is made a signal having a frequency (and amplitude) different from other signals. This allows the control signal and supervisory signal to be superimposed on the clock signal. Therefore fast bidirectional signal transmission between the controller and the controlled section and between the controller and the sensor section can be achieved and the control signal and supervisory signal can be provided onto the common data signal line and transmitted bidirectionally at the same time. As a result, the need to provide separate periods for transmitting the control signal and the supervisory signal on the common data signal line can be eliminated, thus doubling the transfer rate of the signals.
In addition to the components of the common configuration described above, a control and supervisory signal transmission system of the present invention further comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section changes the duty ratio between the period of a predetermined power-supply voltage level and a period of a pseudo ground level according to each value of a control data signal input from the controller in every period of the clock under the control of the timing signal to convert the control data signal into a serial pulse voltage signal and outputs the serial pulse voltage signal onto the data signal line. The parent station input section detects a frequency signal superimposed on the serial pulse voltage signal transmitted over the data signal line in every period of the clock under the control of the timing signal to extract each data value of the serial supervisory signal and converts the data value into the supervisory signal to input the supervisory signal into the controller. Each of the plurality of child stations comprises a child station output section and a child station input section. The child station output section determines the duty ratio between a period of the power-supply voltage level of the serial pulse voltage signal and a period of the pseudo ground level in every period of the clock under the control of the timing signal to extract each data value of the control data signal and outputs data corresponding to the child station in the data value to the corresponding controlled section. The child station input section forms a frequency signal according to a value in the corresponding sensor section under the timing of the timing signal and superimposes the frequency signal on a predetermined position of the serial pulse voltage signal as the data value of the supervisory signal.
According to the control and supervisory signal transmission system of the present invention, the control signal from the controller to the controlled section is made a binary signal (with the power-supply voltage level and another level) having a predetermined duty ratio and the supervisory signal from the sensor section to the controller is made a signal having a frequency (and amplitude) different from other signals. This allows the control signal and supervisory signal to be superimposed on the clock signal. Therefore fast bidirectional signal transmission between the controller and the controlled section and between the controller and the sensor section can be achieved and the control signal and supervisory signal can be provided onto the common data signal line and transmitted bidirectionally at the same time. As a result, the need to provide separate periods for transmitting the control signal and the supervisory signal on the common data signal line can be eliminated, thus doubling the transfer rate of the signals.
In addition to the components of the common configuration described above, a control and supervisory signal transmission system of the present invention further comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, and a parent station output section. The parent station output section changes the duty ratio between the period of a predetermined power-supply voltage level and a period of a pseudo or ground level according to each value of a control data signal input from the controller in every period of the clock under the control of the timing signal to convert the control data signal into a serial pulse voltage signal and outputs the serial pulse voltage signal onto the data signal line. The parent station outputs a start signal onto the data signal line before outputting the serial pulse voltage signal, the start signal having a voltage level equal to the power-supply voltage and a period longer than one period of the clock. The parent station counts clocks extracted from the serial pulse voltage signal to extract an address pre-assigned to the parent station and outputs an end signal. Each of the child stations comprises a child station output section determines the duty ratio between a period of the power-supply voltage level of the serial pulse voltage signal and a period of the pseudo or true ground level in every period of the clock under the control of the timing signal to extract each data value of the control data signal and outputs data corresponding to the child station in the data value to the corresponding controlled section. The child station output section outputs clocks extracted from the serial pulse voltage signal to extract an address pre-assigned to the child station output section and provides data at the address to the corresponding controlled section.
According to the control and supervisory signal transmission system of the present invention, the control signal from the controller to the controlled section is made a binary signal (with the power-supply voltage level and another level) having a predetermined duty ratio. This allows the control signal to be superimposed on the clock signal. As a result, the supervisory signal on the common data signal line can be transmitted with high reliability.